Hiroomi Miyamoto

Tokai University, Hiratuka, Kanagawa, Japan

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Publications (11)25.22 Total impact

  • Masayoshi Sano · Hiroomi Miyamoto · Shuhei Nishida
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    ABSTRACT: A new gregarine species, Thiriotia euchirellae n. sp. (Apicomplexa: Eugregarinorida), is described from the gut lumen of a mesopelagic copepod, Euchirella rostrata (Calanoida: Aetideidae), collected in Sagami Bay, Japan. Thiriotia euchirellae n. sp. has an elongated and cylindrical body with an average length of 174 μm, and is distinguished from its congeners by its shorter and thicker body, the rounded anterior end with thicker folds than for the rest of the body, and the posterior end covered by epicytic folds. Molecular phylogenetic analysis based on nuclear 18S rDNA placed T. euchirellae n. sp. in the clade of eugregarines infecting marine crustaceans, and in the same subclade as T. pugettiae. Thiriotia euchirellae n. sp. infected 95 % of the E. rostrata population, but was not detected in the other mesopelagic copepod species examined in the present study. Euchirella rostrata has an elongated gut with a swollen and sigmoidal anterior part and a gradually narrowing posterior part connected through a narrow path. Thiriotia euchirellae n. sp. were mostly observed in the posterior part of the gut. The high infection rate of E. rostrata by T. euchirellae n. sp. and the characteristic gut morphology of the host suggest a specific host–parasite relationship between these species.
    No preview · Article · Dec 2015 · Marine Biodiversity
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    ABSTRACT: We describe a new species of Crambionella , C. helmbiru , from central Java, Indonesia. The combination of the mean number of lappets per octant (14), presence of foliaceous appendages amongst frills on oral-arms, absence of tubercles on the velar lappets, proportion of terminal club length to oral-arm length (0.28), and the body colour distinguish this species from three previously described congeners. In addition, the analysis of partial sequences of the cytochrome c oxidase subunit I gene indicate substantial genetic differences from both Crambionella orsini and Crambionella stuhlmanni , supporting the validity of this new species. A combination of morphological and genetic approaches determined that the remarkable differences in exumbrellar colours observed in specimens are simply intra-specific variation. Surprisingly, this species has been commercially harvested for more than 20 years and is well-known to the local people in the region, yet it had remained unknown to science until this point. The commercial fisheries targeting this formerly unknown species are also described in detail.
    Full-text · Article · May 2015 · Journal of the Marine Biological Association of the UK
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    ABSTRACT: After the adoption of the Aichi Target, data accumulation and evaluation regarding biodiversity have progressed rapidly. The use of ecologically and biologically significant areas (EBSAs) criteria to evaluate important areas enables the identification of effective and prioritized areas for ecosystem management. This includes strategic environmental assessment and discussions aimed at establishing protected marine areas based on scientific data. This paper reviews previous and current ideas as well as the methods used, for the identification of EBSAs. In particular, the following issues are addressed: problems associated with different types of marine ecosystems in the Japanese Archipelago, such as seagrass and seaweed beds, coral reefs, offshore pelagic plankton, and deep-sea benthic ecosystems; and problems associated with the integration of multiple criteria that are not totally exclusive. Several candidate variables accounting for each of the 7 criteria used to identify ecologically important areas are presented. Data availability is the most important criterion that allowed for the comprehensive evaluation of different types of ecosystems in the same localities. In particular, for coastal ecosystems such as seagrass, seaweed beds, and coral reefs, it is possible to carry out broad spatial comparisons using variables representing most of these 7 criteria. Regarding methods for the quantitative evaluation of each criterion and their integration, application of these methods to kelp forest ecosystems in Hokkaido, Northern Japan is presented as a case study.
    Full-text · Article · Jan 2015 · Marine Policy
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    Hiroomi Miyamoto · Moriyuki Kotori · Hiroshi Itoh · Shuhei Nishida
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    ABSTRACT: We analyzed the species composition of pelagic chaetognaths in the Indo-Pacific region as reported in published papers to demonstrate geographic variation in their species diversity and its relationships with environmental variables. The resulting latitudinal pattern in species richness (SR) was asymmetric to the equator, with a peak at 35°N in the Kuroshio area and a gradual decrease to a minimum at ∼40°S. Shannon's diversity index (H′) showed a similar pattern, except that it plateaued between 20°N and 35°S. Regression analyses and structural equation models (SEMs) showed that temperature was the most important explanatory variable, both for SR and H′. The SEM also demonstrated that chlorophyll a concentration and mixed-layer depth were the second most effective variables for SR and H′, respectively. On the basis of these results, models were constructed to estimate geographical variation in SR and H′. The estimated SR was high in coastal waters in tropical to subtropical areas, while H′ was high at midlatitudes in the open ocean. The present data highlight the importance of the coastal waters of Southeast Asia and the Indian Ocean, but also indicate that a gap still exists in this area, which necessitates further data mining as well as basic research.
    Preview · Article · May 2014 · Journal of Plankton Research
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    ABSTRACT: Coastal habitats having high productivity provide numerous ecological services such as foods, protection from strong waves through buffering effect, fixation of CO2 through photosynthesis, fostering biodiversity etc. However, increasing human impacts and climate change decrease or degrade coastal habitats. ASEAN region is developing most rapidly in the world. In the developing region, it is necessary to grasp present spatial distributions of habitats as a baseline data with standardized mapping methods. Remote sensing is one of the most effective methods for mapping. Japan Aerospace Exploration Agency (JAXA) provides non-commercial satellite images with ultra-high spatial resolution optical sensors (10 m), AVNIR2, similar to LANDSAT TM. Using ALOS AVNIR2 images it may be possible to make habitat map in the region. In Thailand, shrimp ponds cause degradation of coastal ecosystem through cutting mangroves and eutrophicated discharge from ponds. We examined capability of remote sesing with ALOS AVNIR2 to map seagrass beds in Khung Kraben Bay, Chanthaburi Province, Thailand, surrounded by shrimp ponds. We analyzed ALOS AVNIR2 taken on 25 January 2008. Ground truth survey was conducted in October 2010 using side scan sonar and scuba diving. The survey revealed that there were broad seagrass beds consisting of Enhalus acroides. We used a decision tree to detect seagrass beds in the bay with quite turbid seawater coupled with Depth-Invariant Index proposed by Lyzenga (1985) and bottom reflectances. We could succeed to detect seagrass beds. Thus it is concluded that ALOS AVNIR2 is practical to map seagrass beds in this region.
    Full-text · Article · Nov 2012 · Proceedings of SPIE - The International Society for Optical Engineering
  • Hiroomi Miyamoto · Ryuji J. Machida · Shuhei Nishida
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    ABSTRACT: The physical barriers in the meso- and bathypelagic layers of the open ocean are obscure compared with those in terrestrial, coastal, and ocean epipelagic habitats, which has led to the assumption that little genetic structure exists within deep-sea zooplankton species. Here, we show that the deep-sea chaetognath Eukrohnia hamata has differentiated genetically in habitats without obvious physical barriers. A partial nucleotide sequence of the mitochondrial COI gene was determined for E. hamata collected from the Pacific, Atlantic, and Antarctic oceans, with additional sequences from the congeneric species E. bathypelagica, E. bathyantarctica, and E. fowleri. In the resultant tree, E. hamata and E. bathypelagica, as defined by morphological taxonomy, formed a single lineage in which the two are intermixed. Within this lineage (E. hamata + E. bathypelagica) four major clades (Ham-A–D) were recognized, which showed genetic distances comparable to those between E. bathyantarctica and E. fowleri. Ham-A and D were distributed in the Antarctic and the North Pacific Oceans, respectively. Ham-B and C were cosmopolitan groups, with dominant areas in temperate and equatorial regions, respectively. Additionally, the grasping spines were furnished with distally oriented serration only in the Ham-D individuals. Our results provide evidence of genetic structure in the mtDNA of the assemblage of E. hamata and E. bathypelagica and indicate the necessity for further ecological and genetic studies using nuclear markers.
    No preview · Article · Oct 2012 · Progress In Oceanography
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    ABSTRACT: The Tōhoku earthquake and tsunami of March 11, 2011, resulted in unprecedented radioactivity releases from the Fukushima Dai-ichi nuclear power plants to the Northwest Pacific Ocean. Results are presented here from an international study of radionuclide contaminants in surface and subsurface waters, as well as in zooplankton and fish, off Japan in June 2011. A major finding is detection of Fukushima-derived (134)Cs and (137)Cs throughout waters 30-600 km offshore, with the highest activities associated with near-shore eddies and the Kuroshio Current acting as a southern boundary for transport. Fukushima-derived Cs isotopes were also detected in zooplankton and mesopelagic fish, and unique to this study we also find (110 m)Ag in zooplankton. Vertical profiles are used to calculate a total inventory of ~2 PBq (137)Cs in an ocean area of 150,000 km(2). Our results can only be understood in the context of our drifter data and an oceanographic model that shows rapid advection of contaminants further out in the Pacific. Importantly, our data are consistent with higher estimates of the magnitude of Fukushima fallout and direct releases [Stohl et al. (2011) Atmos Chem Phys Discuss 11:28319-28394; Bailly du Bois et al. (2011) J Environ Radioact, 10.1016/j.jenvrad.2011.11.015]. We address risks to public health and marine biota by showing that though Cs isotopes are elevated 10-1,000× over prior levels in waters off Japan, radiation risks due to these radionuclides are below those generally considered harmful to marine animals and human consumers, and even below those from naturally occurring radionuclides.
    Full-text · Article · Apr 2012 · Proceedings of the National Academy of Sciences
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    Hiroomi Miyamoto · Shuhei Nishida · Kazunori Kuroda · Yuji Tanaka
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    ABSTRACT: The vertical distribution and seasonal variation of pelagic chaetognaths was investigated in Sagami Bay, based on stratified zooplankton samples from the upper 1,400 m. The chaetognaths were most abundant in the 100– 150 m layer in January and May 2005, whereas they were concentrated in the upper 50 m in the other months. Among the 28 species identified, Zonosagitta nagae had the highest mean standing stock, followed by Flaccisagitta enflata and Eukrohnia hamata. Cluster analysis based on species composition and density separated chaetognath communi-ties into four groups (Groups A–D). While the distribution of Group C was unclear due to their rare occurrence, the other groups were more closely associated with depth than with season. The epipelagic group (Group A) was further divided into four sub-groups, which were related to seasonal hydrographic variation. The mesopelagic group (Group B) was mainly composed of samples from the 150–400 m layer, although Group A, in which the epipelagic species Z. nagae dominated, was distributed in this layer from May to July. Below 400 m, all samples were included in the bathypelagic group (Group D). In this group, Eukrohnia hamata was dominant with larger standing stocks than in other tropical-temperate waters, suggesting that intrusions of subarctic water drive the large standing stock of this species. Combined, these observations suggest that the seasonal and vertical patterns of the chaetognath community in Sagami Bay are influenced by hydrographic changes in the epipelagic layer and the submerged subarctic water in the mesopelagic layer.
    Full-text · Article · Jan 2012 · Plankton and Benthos Research
  • Hiroomi Miyamoto · Shuhei Nishida
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    ABSTRACT: A new chaetognath, Bathyspadella oxydentata, collected from Sagami Bay, central Japan, is described. The new species was collected from deep-sea benthopelagic habitat and is distinguished from the closely related species Bathyspadella edentata Tokioka, 193917. Tokioka , T. 1939. Three new chaetognaths from Japanese waters. Mem Imp Mar Obs., 7: 129–140. View all references by the presence of teeth. The phylogenetic position of the new species was examined by molecular genetic analysis using partial sequences of 18S rRNA and 16S rRNA. Although B. oxydentata shares several morphological features with both Spadellidae and Eukrohnidae, the molecular phylogeny indicates that the new species is closely related to Heterokrohnidae species.
    No preview · Article · Dec 2011 · Journal of Natural History
  • Hiroomi Miyamoto · Ryuji J. Machida · Shuhei Nishida
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    ABSTRACT: We investigated genetic diversity and structure of the deep sea chaetognath Caecosagitta macrocephala collected in the western North Pacific (Sagami Bay) and eastern Central to South Atlantic. All of the 52 specimens analyzed had unique haplotypes in their mitochondrial cytochrome c oxidase subunit I (mtCOI) gene sequences. Four distinct lineages of the mtCOI gene sequences (mtA, mtB, mtC, and mtD) were revealed by phylogenetic analysis with robust statistical support. The specimens collected from the Atlantic Ocean comprised three of the lineages (mtA, mtB, and mtD). All specimens of the remaining lineage (mtC) were obtained from Sagami Bay. The outgroup node was placed between the mtA lineage and lineages mtB, mtC, and mtD. Two specimens from each of the four lineages were randomly selected and the nuclear ribosomal internal transcribed spacer 1 (nITS1) region sequenced, resulting in ten forms, two of which were shared by all eight individuals. Phylogenetic relationships estimated from these sequences further supported the independence and reproductive isolation of the mtA individuals from the other lineages, while no phylogenetic structure was found in the mtB, mtC, and mtD lineages. These results indicate the presence of at least two cryptic species in C. macrocephala. Interestingly, these cryptic species were collected primarily from different depth layers (meso- and bathypelagic), suggesting speciation of the bathypelagic species from a mesopelagic precursor.
    No preview · Article · Dec 2010 · Deep Sea Research Part II Topical Studies in Oceanography
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    Hiroomi Miyamoto · Ryuji J Machida · Shuhei Nishida
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    ABSTRACT: The complete nucleotide sequences of the mitochondrial genomes were determined for the three pelagic chaetognaths, Sagitta nagae, Sagitta decipiens, and Sagitta enflata. The mitochondrial genomes of these species which were 11,459, 11,121, and 12,631bp in length, respectively, contained 14 genes (11 protein-coding genes, one transfer RNA gene, and two ribosomal RNA genes), and were found to have lost 23 genes that are present in the typical metazoan mitochondrial genome. The same mitochondrial genome contents have been reported from the benthic chaetognaths belonging to the family Spadellidae, Paraspadella gotoi and Spadella cephaloptera. Within the phylum Chaetognatha, Sagitta and Spadellidae are distantly related, suggesting that the gene loss occurred in the ancestral species of the phylum. The gene orders of the three Sagitta species are markedly different from those of the other non-Chaetognatha metazoans. In contrast to the region with frequent gene rearrangements, no gene rearrangements were observed in the gene cluster encoding COII-III, ND1-3, srRNA, and tRNA(met). Within this conserved gene cluster, gene rearrangements were not observed in the three Sagitta species or between the Sagitta and Spadellidae species. The gene order of this cluster was also assumed to be the ancestral state of the phylum.
    Preview · Article · Mar 2010 · Comparative Biochemistry and Physiology Part D Genomics and Proteomics

Publication Stats

172 Citations
25.22 Total Impact Points


  • 2015
    • Tokai University
      • School of Marine Science and Technology
      Hiratuka, Kanagawa, Japan
    • Tohoku National Fisheries Research Institute
      Miyazu, Kyōto, Japan
  • 2010-2014
    • The University of Tokyo
      • Institute of Atmosphere and Ocean Research
      白山, Tōkyō, Japan
  • 2012
    • Tokyo University of Marine Science and Technology
      • Graduate School of Marine Science and Technology
      Edo, Tōkyō, Japan